1044 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1952 



Fig. 16 — Contacts maj' be gang adjusted to operate at the proper points in the 

 armature travel by bending the arms of the core plate with a screwdriver. 



stationary contacts and the make twin contacts, thereby causing these 

 contacts to operate earher in the armature travel. Since the break twin 

 contacts rest against the stationary contacts, these are also moved to the 

 left, reducing the space between the break twin wires and the actuating 

 surface of the card. Thus, bending the core plate arms to the left causes 

 both make and break contacts to operate earlier in the armature travel, 

 while bending the arms to the right causes these contacts to operate 

 later. By bending both arms in the same direction, the operate points 

 of all contacts may be shifted in the same direction. On the other hand, 

 separate arms permit adjustment of the upper relay contacts independ- 

 ently of the lower contacts, thereby increasing the latitude of adjustment. 



The parts of the relay are dimensioned so that no adjustment of the 

 core plate arms is rec^uired, except to compensate for variations in manu- 

 facture of the relay parts. Hence relays assembled from parts made with 

 sufficient accuracy do not generally require adjustment. 



The restoring springs ma}' be adjusted for the proper armatiu'c back 

 tension by the use of a simple spring bending tool applied to the side 

 arms. However, springs are pro^'ided with various predeflections and 

 thicknesses to correspond with various numbers of make twin contacts 

 which must be held open in the unoperated position. Again, no adjust- 

 ment for back tension is necessarj' except to compensate for variations 



